Automatic switch



sept. 26, 1933. E T. FORD 1,927,934

AUTOMATIC SWITCH Filed July 9, 1931 2 Sheets-SheetA 2 :nl La .T8 di J3 i JJ 75 J2 74 l u u 2 i; if /45 65 7^? E J0 60 J6 7l 7a l. 64 da 49 47 1 @METALL/c 46 i 45 67 69 P IL/ s Il j? L@ nvenor."

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Patented Sept. 26, 1933 UNITED STATES PATENT OFFICE Application July 9, 1931.

Serial N0. 549,619

This invention relates to automatically operated electric switches and more particularly to temperature controlled and pressure operated switches such for example as used for automatically controlling the operation of electrically actuated heating, gas and oil burning, pumping, refrigeration and analagous equipment.

An object of this invention is to provide an automatic switch which will be superior to automatic switches such as heretofore produced, by reason of its comparative simplicity and inexpensiveness of construction, its reliability and precision of operation, and the provision for an accurate functioning thereof over long periods of time without requiring delicate adjustment and frequent servicing, and also by reason of its ruggedness, compactness and ease of adaptability and installation.

Another object of this invention is to provide an automatic circuit control mechanism wherein the switch means includes a movable contact member arranged to be operated with a quick snap action, in a particularly elcient manner, said switch means being exceptionally simple as to construction, inexpensive, strong, durable, capable of easy yet accurate adjustment, most reliable and accurate in operation at all times, and also subject to efficacious operation by thermostatic or pressure actuated means.

With the foregoing objects in view, together with such other objects and advantages as may subsequently appear, the invention resides in the parts and in the combination, construction and arrangement of parts hereinafter described and claimed and illustrated by way of example in the accompanying drawings, in which:

Figure 1 represents a front elevation of an automatic switch of this invention;

Figure 2 is a vertical sectional view taken on the plane of line 2 2 of Figure 1;

Figure 3 is asectional View taken on the plane of line 3--3 of Figure 2;

Figure 4 is an enlarged fragmentary front elevation of one part of the regulating means of the switch;

Figure 5 is a sectional view taken on the plane of line 5-5 of Figure 4;

Figure 6 is a front elevation of a modied form oi' the switch;

Figure 7 is a front elevation of another modified form of the switch;

Figure 8 is a sectional view taken on the plane of line 8 8 of Figure 7.

One embodiment of this invention, as shown in detail in the accompanying drawings, includes a casing 1 within which is mounted a switch means 2, a thermostat 3 and a regulating means 4. These elements are arranged in a small compact group with a lever 5 of the regulating means extending through a slot 6 in the front wall 7 of 60 the casing whereby the mechanism may be readily adjusted and set to operate at diierent temperatures.

The switch means 2 comprises a contact screw 8 longitudinally adjustably supported in an insulation block 9 xed on the rear wall- 10 of the casing 1, there being a lock nut 11 on said contact to maintain it in adjusted positions. Electrically connected with this contact is a binding post 12 which is supported on the block 9. 7

Arranged to be flexed into and out of engagement with an end of the contact 8 is a movable spring contact 14, as here shown, on the form of a leaf spring. One end of this spring contact is xed as at 15 to the outer end of the support- 7 ing and conducting arm 16 carried by said block 9 whereas the other end of the Contact is disposed adjacent the contact 8 so that a at face of the contact 14 is opposite the contact 8, it being noted that the opposed portions of said contacts carry the usual contact points 17. The contact 14 is exed so that it normally eiects a contact with the contact 8 and is moved out of contacting position against the spring action thereof. On the arm 16 is a binding post 18 which with the 85 binding post l2 provides for electrically connecting the contacts 14 and 8 in the circuit to be controlled.

Means of connection is provided between ther- 9o mostat 3 and the spring contact 14 whereby said contact will be moved with a snap action clear of contact 8 when the thermostat is actuated.

As here shown, such means comprises an arcuate resilient link 20 hinged as at 22 to the outer end of the spring contact, and likewise hinged as at 23 to the end 25 of the thermostat. It is noted that the thermostat coil is in the form of a flat spiral coil having the inner end thereof mounted to rotate on a post 26 fixed to the rear wall of the 100 casing 1. In instances where the switch is arranged to open at a predetermined increased temperature, the strip of thermostatic metal comprising the thermostatic coil is arranged so that the coil will contract under increasing temperatures and expand with decreasing temperatures and consequently when the coil contracts the end 25 thereof will move so as to exert a downward and outward pressure on the bowed link 20 which will therefore act to move the contact 14 clear 110 of contact 8 with a snap action. It is obvious that with a reverse arrangement of -said coil the switch may be operated to open at predetermined decreased temperatures.

',Io provide for controlling the operation of the thermostat and to regulate the entire mechanism whereby it may be set to operate at different temperatures, the regulating means 4 is employed to vary the tension or action of the thermostat coil. As here shown, a crank arm 30 is iixed to the inner end of the thermostat coil and pivotally mounted on the post 26 in such manner that on appropriate movement said crank arm will expand or contract the coil. To provide for movement of this crank arm the lever 5 is pivtally connected with a casing carried bracket 32 and operates a cam 33'which engages said arm.

It is now seen that upon moving the lever 5 in one direction the cam 33 will engage and cause the crank arm 30 to be moved so as to contract the thermostat coil where as opposite movement of said lever will cause the crank arm to move so as to expand said coil. It is noted that the arrangement is such that the part of the regulating means will remain by friction in the various positions oi adjustment whereby to maintain the thermostat adjustment. It is obvious that inasmuch as the thermostat coil actuates the switch when it is contracted to a predetermined extent, that by means of the adjusting means 4 the coil may be adjusted to various degrees of contraction whereby the switch operating contraction point of the coil will occur at different temperatures as desired depending upon the use to which the mechanism of the invention is put.

It should be noted that the link 20 is bowed and resilient to provide a delayed action in actuating the switch whereby switch is opened with a quick or snap movement. This link, however, need not be bowed inasmuch as any form of link will transmit the force of the thermostat, in such manner as to impart a snap opening action to the switch and permit of a similar switch closing action, will be satisfactory.

Preferably the cam 33 is adjustable relative to the lever 5 where further control and regulation of the thermostat may be had. As here shown, the lever 5 is pivoted at one end, as at 35, to a point between the ends of the cam. At a point spaced inwardly from said end said lever is provided with an arcuate slot 34 concentric with the pivot 35 and this slot registers with a threaded opening 36 in the cam. A set screw 37 is inserted through the slot and turned in the opening whereby when tightened it will hold the lever and cam against relative movement. The cam is pivoted as at 38 upon the bracket 32, and the operating or cam face 40 of the cam is provided in one end of the plate or strip comprising the cam. This plate or strip is doubled back upon itself whereby the face 40 is disposed between the pivots 38 and 35 in position to engage the crank arm 30. It is now apparent that upon loosening the screw 37 the lever may beturned on the pivot 35 relative to the cam and screw then tightened whereby to vary the cam action when the lever is manipulated and thereby regulate the action of the thermostat. This arrangement permits of adjustment of the lever to positions opposite the various temperature indications B marked on the casing and provides an accurate response of the mechanism to the set positions of the lever.

The modiiied form ofthe invention shown in detail in Figure 6 is especially designed for controlling the electrical equipment associated with brine tanks, cabinets, display cases and coolers wherein it is impossible to include the control unit in the cold chamber.

In this form the device includes a switch mechanism 40, identical in construction to the switch mechanism of the iirst described form of the invention, but having a different form of thermostat and control means. Here, the thermostat means is of semi-remote type and comprises a bellows type thermostat 41 arranged in a casing 42 exteriorly of the main casing 43. Extending from the thermostat is the remote control means 44 arranged to be connected to the remote chamber notshown, to be controlled in the manner commonly followed in the art, whereby the temperature change at said remote point is effective through said means at the thermostat 41.

A plunger 45 rests upon and is actuated by the thermostat 41, to engage and move a lever 46 which is pivoted as at 47 between its ends to a bracket 48 of the switch mechanism 40. One end of this lever is hingedly connected as at 4i) with the link 50 of the switch, whereas the other end of the lever normally rests on a supporting lug 51 carried by the casing 43. Movement of the lever to close the switch, is resisted by a helical spring 52 having a tension adjusting nut 53 turnable on an adjusting screw 54 on which latter the spring and nut 53 are movable bodily to regulate the tension of said spring. A plate 55 is iixed to the spring 52 and has a central bearing point 105 56 which engages the upper side of the lever 46.

By varying the tension of the spring 52 the mechanism may be set to operate at different temperatures.

In this form of the invention the thermostat is arranged to be contracted by a lowering temperature until the force of the spring 44 will be effective to rock the lever 46 downward in such manner that the spring contact member 58 by its inherent resiliency will move quickly and with a snap action out of circuit closing engagement with contact member 59. As 'the temperature rises the thermostat expands and rocks the lever 46 upward against the iniluence of spring 44 and the spring contact moves due to inherent resiliency, with a snap action back into circuit closing position. It will be noted that the lever 46 has a binding post 60 thereon whereas a binding post 61 is electrically connected with the contact 59. The link 50 is preferably thermostatic and bowed in such manner that it will tend to contract or bow further under the influence of rising temperatures whereby to compensate for the effect of high atmospheric temperatures on the parts of the thermostat exposed to said high temperatures. In hot climates the thermostat will be expanded to an extent that would cause objectionable errors in the operation of the mechanism unless the aforesaid compensating action is provided. Thus it is seen that the link 50 automatically compensates for unintentional expansion of the thermostat and thereby insures an accurate operation of the switch at the predetermined temperature regardless of the eifects of high atmospheric temperatures on said thermostat.

Another modied form of the invention as shown in Figures 'l and 8 is identical with the other forms in respect to the switch means here designated 63, but differs as to the thermostatic operating means. In this form the thermostatic means comprises an elongated tubular casing or pipe 64 arranged to be extended from the casing 65 into the chamber, tank, vat or the like to be controlled in such manner that the switch mechanism may be disposed exteriorly of or well spaced from said chamber etc. A helically coiled thermostatic element 66 is arranged in said tubular casing and operates on rising temperatures to rotate a shaft 67 connected thereto and extended into the casing in such manner that the switch means 63 will be operated to open the electrical circuit under control.

As here shown, the shaft 67 has a crank arm 68 fixed thereto and arranged to be rested upon an adjusting screw 69 l operable exteriorly of the casing 65. Upon turning this screw the crank arm 68 operates to turn the shaft.67 whereby the tension of the helically coiled thermostat may be varied as desired to regulate the control action of the unit.

To provide for operative connection of the shaft 67 with the switch means 63 another crank arm 70 is adjustably xed to the shaft by a set screw 71. The crank arm 70 is connected to the link 72 of said switch means in such manner that the latter will act to flex the spring contact 73 out of engagement with contact 74 when the thermostat 66 responds to the predetermined temperature to which it is exposed, operates to turn the shaft 67 and through crank arm 70 tends to move the link towards the c ontact member '73. In this modification the thermostat is arranged to open the switch on increasing temperatures and to close the switch when the temperature drops. However, it is obvious that this form of this invention may also be used in connection with refrigeration and other equipment where the switch is opened on descending temperatures and closed on ascending temperatures, by simply reversing the action of the thermostat.

While the embodiments as herewith disclosed are operated by thermostatic means, it is obvious that pressure actuated means could be used to actuate the switch mechanism of said embodiments whereby to open and close the switch at predetermined pressures as desired, without departing from the spirit and scope of this invention.

It should be noted that the point of contact of the spring contact member 14 as shown in Figure 3, with the fixed Contact member 8 is spaced inwardly from the outer end of said spring contact and that the spring contact bows inward between its ends when the switch is closed. Said contact point is also spaced outwardly from a straight line drawn through the points of xation of the outer ends of the link 20 and contact member 14. These arrangements insure the quick snap action or movement of the contact 14 so as to prevent arcing and pitting or burning of the contacts as a result of such arcing. The corresponding spring contact members and link members of the other forms of the invention shown in Figures 6 and 7 are arranged as are the contact member 14 and link 20. Thus it is seen that the member 14 and link 20 comprise a sectional or articulated switch or contact member which stores up the forces transmitted thereto by the thermostatic switch actuating means, and by reason of the inherent resiliency thereof, the articulated joint and the aforesaid arrangement, suddenly releases the said forces whereby to cause a quick movement of contact 14 into and out of operative position.

It will now be apparent that the mechanism of this invention provides for the objects and advantages hereinbefore noted in a particularly efficacious manner.

I claim:

1. In a thermostat switch, a supporting structure, a fixed contact member on said supporting structure, a spring contact member fixed adjacent one end to said support and arranged to be exed into and out of contact with the fixed contact member, a thermostat, and a link connecting said thermostat with the other end of said spring contact member, and being supported solely by and between said thermostat and spring contact member.

2. In a thermostat switch, a supporting structure, a fixed contact member on said supporting structure, a spring contact member fixed to said support and arranged to be flexed into and out of contact with the fixed contact member, a thermostat, and a thermostatic link connecting said thermostat with said spring contact member.

3. In an automatic switch, a supporting structure, a xed contact member thereon, a leaf spring contact fixed at one end to said supporting structure and arranged to be exed into and out of position of contact with said flxed contact member, an actuator on said supporting structure, and a bowed member hinged to the other end of said spring contact member and operatively connected with said actuator.

4. In a thermostat switch, a supporting structure, a fixed contact member thereon, a spring contact member xed at one end to said supporting structure and arranged to be exed into and out of position of engagement with said fixed contact member, a thermostat, an arm actuated by said thermostat, a bowed resilient member connected at its ends with said arm and the other end of said spring contact member, said bowed resilient member operating with the thermostat to normally hold the spring contact member under tension and in contact with said fixed contact member.

5. In a thermostat switch, a fixed contact member, a leaf spring contact member arranged to normally and by its inherent resiliency maintain a contact with said fixed contact member, a thermostat, and a link connected with said thermostat and said spring contact and operating to move the spring contact into and out of engagement with said fixed contact upon expansion and contraction of said thermostat, said link being thermostatic and arranged to vary the action of said thermostat.

6. In a thermostat switch, a fixed contact member, a leaf spring contact member arranged to normally and by its inherent resiliency maintain a contactwith said fixed contact member, a thermostat, and a link connected with said thermostat and said spring contact and operating to move the spring contact into and out of engagement with said fixed contact upon expansion and contraction of said thermostat, said link being thermostatic and arranged to vary the action of said thermostat, said link being bowed in the direction of movement of the spring contact when the latter moves clear of said flxed contact.

7. In a thermostatic switch, a supporting means, a contact xed thereon, a. leaf spring contact xed at one end to said means and normally engaging under the influence of its inherent resiliency and at a point near but spaced inwardly from its other end, said xed contact, a thermostat, and a bodily movable link connecting said thermostat with said other end of said spring contact and being supported solely by and between said spring contact and said thermostat.

8. In an automatic switch, a supporting means.

a contact fixed thereon. a movable contact fixed to said means and adapted to engage said fixed contact, a resilient actuator, and a bowed link connecting said actuator with an end of said movable contact, a thermostat associated with said actuator, and means for regulating the action of said actuator operative to vary the action of the thermostat.

9. In a thermostatic switch, a supporting means, arcontact fixed thereon, a spring contact fixed at one end to said means and normally engaging under the influence of its inherent resiliency and at a point near but spaced inwardly from its other end, said fixed contact, a thermostat, and a bodily movable link hingedly connected at its ends with said thermostat and said other end of said spring contact.

10. In a thermostat switch, a supporting means, a contact fixed thereon, a leaf spring contact fixed at one end on said supporting means and arranged to normally engage at a point be- ,tween its ends and under the infiuence of the inherent resiliency thereof, said fixed contact, a thermostat element, and a link connected with the other end of said thermostat and the other end of said spring contact, the point of engagement of said contacts being spaced outwardly from a straight line passing through the points of fixation of the outer ends of said link and said spring"contact member.

11. In a thermostat switch, a supporting means, a contact fixed thereon, a leaf spring contact fixed atvone end of said supporting means and arranged'to normally engage at a point between its ends and under the infiuence of the inherent resiliency thereof, said fixed contact, a coiled thermostat element, means securing the inner end of said element to said supporting means, a link connected with the outer end of said thermostat and the other end of said spring contact, and means for moving the inner end of said element to vary the tension of said element.

12. In a thermostat switch, a supporting means, a contact fixed thereon, a leaf spring contact fixed at one end of said supporting means and arranged to normally engage at a point 4between its ends and under the infiuence of the inherent resiliency thereof, said fixed contact, a coiled thermostat element, means securing the inner end of said element to said supporting means, a link connected with the outer end of said thermostat and the other end of said spring contact, means for moving the inner end of said element to vary the tension of said element, said last named means comprising a lever, a cam thereon pivotally connected with said supporting means, and a crank arm on said inner end of said element arranged to engage said cam.

13. -In an automatic switch, a supporting means, a contact member thereon, a movable contact member fixed to said supporting means and arranged to engage said first named contact, an actuating means, and a resilient link connecting said movable contact -with said actuating means and operating to move said movable contact member into and out of contact with the first namedcontact upon operation of said actuator.

14. In an automatic switch, a supporting means, a contact member fixed thereon, a resilient contact member fixed at one end to said support and arranged to engage near its other end and under the infiuence of its inherent re` siliency, said fixed contact member, a lever pivoted between its ends on said supporting means, a link connecting one end of said lever with the outer end of said resilient contact member, a spring means resisting movement of said lever in one direction, and an actuator operable to move the lever against the action of said spring means and to permit the lever to be moved by said spring means.

y 15. In an automatic switch, a supporting means, a contact member fixed thereon, a resilient contact member fixed at one end to said supporting means and arranged to be fiexed into and out of contact with said fixed contact member, a rotary shaft, an actuator operable to turn said shaft, a, crank arm on said shaft, and a resilient link connecting said crank arm with said resilient contact member.

16. In switch mechanism, a supporting means, a contact member fixed thereon, a resilient contact member fixed at one end to said supporting means and arranged to be held in engagement between its ends with said fixed contact, under the influence of the inherent resiliency thereof, an actuator, and a link connected at one end to the other end of said resilient contact and at its other end to said actuator, said resilient contact being bowed inwardly between its ends when in contacting position.

1'7. In a thermostatic switch, a support, a fixed contact thereon, a movable contact member mounted on said support and arranged to be moved into and out of contact with said fixed contact, a thermostatic actuator, and a self compensating link connected at its ends with and supported by and between said actuator and said spring contact member.

18. In an automatic switch, a fixed contact member, a. movable contact member arranged to be moved into and out of contact with said fixed contact, a thermostatically operated actuator, and a bowed link connected at its ends with said actuator and said movable contact member.

ETHELBERT T. FORD. 

